InsertCategory displays all existing categories. You can then assign the page you are on to one or more of these existing categories. On top of this, you can create new categories here too. The dialogue can be called up from both the "Edit" mode and the "View" mode.

This extension was originally made for BlueSpice. BlueSpice is a MediaWiki distribution for enterprises and organizations. It enhances MediaWiki, in particular in the areas quality management, process support, administration, editing and security.